While we're there, I think the right prefixes to ignore are ('http://', 'https://', '//', 'data:') — that would avoid False positives on URLs such as http_ftw/css/mysite.css, and also support protocol-relative URLs.

Fixed #17455 -- Extended CachedStaticFilesStorage slightly to handle some URLs better that are used to add support for webfonts to IE 6-8. Also ignore data: URLs and fragment-only URLs (e.g. #default#VML).